Aspiviridae

Aspiviridae, formerly Ophioviridae, is a family of segmented negative-strand RNA viruses which infect plants. Member viruses are characterized by an elongated and highly filamentous and flexible nucleocapsid with helical symmetry.^[1] It is a monotypic taxon containing only one genus, Ophiovirus. Aspiviridae is also the only family in the order Serpentovirales, which in turn is the only order in the class Milneviricetes.^[2]

Ophiovirus
(top) Electron micrograph of Citrus psorosis ophiovirus; (bottom) Mirafiori lettuce big-vein virus genome
Virus classification
(unranked):	Virus
Realm:	Riboviria
Kingdom:	Orthornavirae
Phylum:	Negarnaviricota
Class:	Milneviricetes
Order:	Serpentovirales
Family:	Aspiviridae
Genus:	Ophiovirus
Species
See text

Collapsed form of the large Freesia sneak ophiovirus particle. Negative-contrast electron micrograph (uranyl acetate); bar: 100 nm.

History

The name Aspiviridae derives from the Latin aspis (snake or viper), referring to the shape, along with the suffix for a virus family -viridae.^[3] Ophiovirus derives from the Ancient Greek ophis, "snake", with –virus the suffix for a virus genus.^[4] Likewise, Serpentovirales is from "serpent" with -virales the suffix for a virus order.^[3] Milneviricetes is in honor of Robert G. Milne, the last author on the first paper describing ophioviruses.^[3][5]

Virology

Structure

The protein capsid is non-enveloped and has a constant diameter of 1500–2500 nm and a width of 3 nm, or 9 nm. The capsids form kinked circles, which can collapse to form linear duplex structures, much like a spring.^[2]

Genome

Member viruses have segmented, negative-sense, single-stranded RNA genomes. The entire genome is 11000–12000 nucleotides long.^[2][6]

Taxonomy

Aspiviridae phylogenetic tree

The family has one genus, Ophiovirus, which has eight recognized species. Members of both the family and the genus are referred to as ophioviruses.^[2] Ophiovirus contains the following species, listed by scientific name and followed by the exemplar virus of the species:^[7]

• Ophiovirus capsici, Pepper chlorosis associated virus
• Ophiovirus citri, Citrus psorosis virus
• Ophiovirus freesiae, Freesia sneak virus
• Ophiovirus lactucae, Lettuce ring necrosis virus
• Ophiovirus mirafioriense, Mirafiori lettuce big-vein virus
• Ophiovirus ranunculi, Ranunculus white mottle virus
• Ophiovirus tulipae, Tulip mild mottle mosaic virus
• Ophiovirus vaccinii, Blueberry mosaic associated virus